// the code inside the loop routine runs over and over again forever:
void loop()

{
digitalWrite(led1, HIGH); // turn the LED on (HIGH is the voltage level)
delay(100); // wait for one-tenth of a second
digitalWrite(led, LOW); // turn the LED off by making the voltage LOW
delay(100);
{digitalWrite(led2, HIGH);
delay(100);
digitalWrite(led2, LOW);
delay(100);}
{digitalWrite(led3, HIGH);
delay(100);
digitalWrite(led3, LOW);
delay(100);}// wait for a second
}

What you can vary in the code :-

The circuit that i assembled and the code given is for three led’s what you can do is to assemble the circuit for two led’s and write the code for alternate blinking of the two led’s. You can change the delay time of both the led’s and you may also change the delay of one led and keep the other same.

Prerequisite :-

You must be familiar with the blink program i created on the breadboard using a single LED. This will help you to set up the circuit by simply reading the code. I will strongly recommend to go through the older page where i created the program for a single LED before trying this one.